
/* 第一次修改 */

* {
  padding: 0;
  margin: 0;
}
.father1 {
  width: 200px;
  height: 200px;
  border: 1px saddlebrown solid;
  position: relative;
  margin: 0 auto;
  display: flex;
  justify-content: center;
  align-items: center;
}
.father1 .son1 {
  position: absolute;
  top: 50%;
  left: 50%;
  
  width: 100px;
  height: 100px;
  border: 1px red solid;
  transform: translate(-50%, -50%);
  background-color: aqua;
}
.father2 {
  margin: 0 auto;
  width: 200px;
  height: 200px;
  border: 1px saddlebrown solid;
  position: relative;
}
.father2 .son2 {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  width: 100px;
  height: 100px;
  border: 1px red solid;
  margin: auto;
  background-color: rebeccapurple;
}
.father3 {
  margin: 0 auto;
  width: 200px;
  height: 200px;
  border: 1px saddlebrown solid;
  display: grid;
  place-items: center;
}
.father3 .son3 {
  width: 100px;
  height: 100px;
  border: 1px red solid;
  background-color: red;
}
.father4 {
  margin: 0 auto;
  width: 200px;
  height: 200px;
  border: 1px saddlebrown solid;
  display: flex;
  justify-content: center;
  align-items: center;
}
.father4 .son4 {
  width: 100px;
  height: 100px;
  border: 1px red solid;
  text-align: center;
  line-height: 100px;
  background-color: #8c64b3;
}
table {
  width: 100%;
  height: 100vh;
  border-collapse: collapse;
}
td {
  text-align: center;
  vertical-align: middle;
}
.box {
  display: inline-block;
  width: 200px;
  height: 200px;
  border: 1px solid black;
}
